| Bolt size no. or inches | Threads per inch (TPI) | |
|---|---|---|
| Coarse thread UNC | Fine thread UNF | |
| #0 | – | 80 |
| #1 | 64 | 72 |
| #2 | 56 | 64 |
| #3 | 48 | 56 |
| #4 | 40 | 48 |
| #5 | 40 | 44 |
| #6 | 32 | 40 |
| #8 | 32 | 36 |
| #10 | 24 | 32 |
| #12 | 24 | 28 |
| 1/4 | 20 | 28 |
| 5/16 | 18 | 24 |
| 3/8 | 16 | 24 |
| 7/16 | 14 | 20 |
| 1/2 | 13 | 20 |
| 9/16 | 12 | 18 |
| 5/8 | 11 | 18 |
| 3/4 | 10 | 16 |
| 7/8 | 9 | 14 |
| 1 | 8 | 12 |
| 1-1/8 | 7 | 12 |
| 1-1/4 | 7 | 12 |
| 1-3/8 | 6 | 12 |
| 1-1/2 | 6 | 12 |
| 1-3/4 | 5 | — |
| 2 | 4-1/2 | — |
| 2-1/4 | 4-1/2 | — |
| 2-1/2 | 4 | — |
| 2-3/4 | 4 | — |
| 3 | 4 | — |
| 3-1/4 | 4 | — |
| 3-1/2 | 4 | — |
| 3-3/4 | 4 | — |
| 4 | 4 | — |